Apparatus for producing carbon dioxide



Get 17, 1967 G H, MAYNARD 3,347,221

APPARATUS FOR PRODUCING CARBON DIOXIDE Filed April 15, 1965 aaazaaq/wwzfl I N VE N TOR.

United States Patent 3,347,221 APPARATUS FOR PRODUCING CARBON DIOXIDE George H. Maynard, Stanstead Abbots, England, assignor to Scheu Steel Supply Company, a corporation of California Filed Apr. 13, 1965, Ser. No. 447,858 2 Claims. (Cl. 126-85) This invention relates to apparatus for increasing the carbon dioxide content of the atmosphere in spaces where plants are grown; for example, in glass-houses and other horticultural enclosures.

The object of the invention is to provide a burner which produces carbon dioxide by the combustion in air of carbonaceous fuel, while avoiding the risk of contaminating the atmosphere with carbon monoxide and aldehydes, and of fire which can arise as a result of burning foreign matter, such as leaves and dust, falling on to straw bales or other dry ignitable bases. A further object is to provide such a burner which is easy and safe to ignite and operate, and in which the fuel supply is automatically cut off in the event of the flame becoming inadvertently extinguished.

According to the invention, apparatus for increasing the carbon dioxide content of the atmosphere in spaces where plants are grown includes a burner, a tray beneath the burner for catching any burning foreign matter, a wall or skirt surrounding the burner to assist in protecting it from draughts, and a canopy above, but spaced from, the wall to protect the burner from moisture or other matter that may fall on the apparatus. Preferably the canopy overlaps the remainder of the apparatus so as the better to protect it from any falling moisture, such as condensation. Advantageously, a member, such as a hook is provided above the canopy to enable the apparatus to be suspended from the roof of a glass house.

The burner may be arranged to burn gas, such as propane gas, and conveniently it may be arranged to produce an annular flame with a vertical axis, the apparatus being designed so that the flame does not actually touch any other part of the assembly. A thermostatic device is preferably provided for sensing the presence of a flame in the vicinity of the burner and for cutting oif the fuel supply it the flame is extinguished inadvertently.

In order that the invention may be clearly understood and readily carried into effect, one construction in accordance therewith will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a side elevation partly in section.

FIGURE 2 is a view taken along line 2-2 of FIG- URE 1.

FIGURE 3 is a view taken along line 33 of FIG- URE 2.

The apparatus shown in the drawing is arranged to be hung from the roof, for example from the central ridge beam, of a glasshouse, or from the cave beam between two spans of a glasshouse having more than one span. For this purpose it is furnished with an axial hook I which projects through the center of a conical canopy 2, the extent permitted by a stop, such as a nut, that bears against the inside of the canopy. The height at which the apparatus is hung depends on the height of the crops in the glasshouse. The canopy 2 is formed from a circular disc, for example by pressing, and has a beaded edge.

Four flat, vertical ties 3, equidistantly distributed round the canopy 2, extend downwards therefrom, the upper ends of the ties 3 being bent so as to enable them to be Welded to the inside surface of the canopy. A skirt 4 surrounds and is carried by the ties 3, the skirt being supported by screws 5 screwed into holes near the lower ends of the ties 3.

3,347,221 Patented Oct. 17, 1967 The lower ends 3:: of the ties 3 are bent inwards to provide flanges that support a circular tray 6 formed with straight edges where it abuts against the ties 3. The tray 6 is covered with a large number of small perforations and is formed centrally with a one-inch diameter hole, through which projects a vertical, circular mixing tube 7 wherein a propane-air mixture is formed during the operation of the apparatus. An annular plate 8 is welded to the top of the tube 7, the plate 8 having a bevelled, circular opening 9, the inner diameter of the opening 9 being equal to the inner diameter of the tube 7. The plate 8 provides the base of a circular burner B, the top being constituted by a head disc 10. Between these two members is clamped a series of rings 11. Alternate rings consist of simple flat annuli, interleaved with corrugated annuli. Each corrugated annulus has radial corrugations equidistantly pitched around the annulus. A pack of rings such as this is described in the specification of prior British Patent No. 892,067. The effect is to provide a large number of radial passages, each defined between a plane and a corrugated ring face, through which the mixture passes to maintain an annular flame around the periphery of the pack. The rings 11 are made thick enough to provide suflicient cooling to prevent flash back and to give good flame stability in conditions of varying gas pressure. A circular cup-shaped deflector 12 is fixed centrally beneath the head disc 10, the deflector being formed with a shank 13 that is forced through a hole in the disc 10 and riveted over the top of the disc.

The burner and mixing tube assembly is supported on the tray 6 through the medium of three bolts 14 distributed equidistantly about the burner axis and serving also for clamping together the disc 10, rings 11 and plate 8. For the last-mentioned purpose a nut 15 is screwed on to each bolt 14. The bolts 14 pass inside the rings 11 in positions such as to engage the inner edges of the rings and located them radially. The bolts 14 pass through holes in the tray 6 .to which they are secured by pairs of nuts 16.

The canopy 2, ties 3, skirt 4 and tray 6 are made of vitreous enamelled mild steel. The plate 8, disc 10 and mixing tube 7 are of mild steel. The rings 11 are of stainless steel or other heat-resisting metal. The deflector 12 is of brass.

The propane gas is admitted to the mixing tube 7 through a jet 17 and the air through holes 18 in the tube wall. The holes 18 are surrounded, with some clearance, by a gauze air filter 19 mounted between caps 20. The jet 17 is fitted into the upper end of a vertical passage 21 through a block 22, which is formed with a spigot 23 that is screwed into a ring 24 welded into the lower end of the tube 7. A line mesh filter 17a is fitted ahead of the jet 17. The passage 21 has a lateral branch 25 to which a pressure gauge 26 is fitted. Thus, the pressure gauge responds to the pressure in the block 22 and, during the operation of the apparatus, this corresponds to the quantity of carbon dioxide being generated, so that the gauge can be graduated in rates of formation of carbon dioxide, and in rates of consumption of propane gas.

The lower end of the block 22 is formed with a tapered spigot 27 on a flame failure valve assembly 28 of known construction. A nipple 29 enables this assembly to be connected by a flexible pipe to a cylinder containing propane gas under pressure located outside the glasshouse.

To start the operation of the apparatus, a press button 30 is depressed to open a valve in the assembly 28 and this causes propane gas to pass through the jet 17 and a propane-air mixture to travel along the tube 7 to be deflected by the deflector 12 through the rings 11 so as to be discharged around the periphery of the bum- J er B. The gas is ignited by a match inserted through or just below a half-inch diameter hole 6a in the tray 6, just beyond the periphery of the burner B. The button 30 is kept depressed for about thirty seconds, during which time a thermocouple (hot-junction) tip 31 becomes heated and generates a thermo-electric current, which passes along a lead 32 to energize an electromagnet in the assembly 28. This electromagnet serves to hold the valve open, even after the button 30 is released. If, for any reason, the flame fails, the tip 31 cools rapidly so that the electromagnet becomes de-energized and allows a spring to close the valve and cut off the propane gas from the burner. A needle valve is controlled by a knob 33 which is turned to adjust the pressure of the gas passing to the valve assembly 28.

The tray 6 provides complete protection for the hand while the burner is being ignited and also prevents any burning foreign matter from falling to the ground. The small perforations in the tray provide for a diffused and steady flow of secondary air, which ensures that the combustion of the propane gas is complete and elimi-- nates any risk of carbon monoxide poisoning. The tray 6, together with the skirt 4 and canopy 2, combine completely to protect the flame from draughts coming from those directions in which the draughts are most likely to arise when the apparatus is hanging in a glasshouse. Such draughts could, otherwise, also give rise to carbon monoxide as well as aldehydes harmful to plants. The canopy, skirt and tray also protect the burner from the spraying that has to be done in glasshouses. The canopy protects the parts, particularly the burner, that. lie beneath it from the effects of any condensation that may drip from the roof of the glasshouse. The carbon dioxide is discharged in all direction between the canopy and the skirt so as to give an even distribution of carbon dioxide throughout the glasshouse. As soon as the gas cools, it diffuses through the air in the glasshouse.

The annular flame around the burner B curves upwards so that it has a saucer shape as a result of the secondary air currents rising through the tray 6. The flame, therefore, does not impinge on any metal surfaces.

The apparatus shown in the drawing is twenty-one inches high and has. a diameter of thirteen inches. It can be dismantled so as to pack into a cube having a thirteeninch side. It can produce six pounds of carbon dioxide per hour and, if one such apparatus is used per tenth of an acre glasshouse area, it enriches the atmosphere to about 0.10% carbon dioxide, as compared with the normal concentration of about 0.033%. In winter, this has the further advantageous effect of raising the glasshouse temperature by about four degrees Fahrenheit in average conditions.

In an alternative arrangement a pilot burner is provided close to the edge of the burner B, the thermocouple tip 31 being arranged to sense whether the pilot burner is alight or not, so that the flame failure valve cuts oflf the supply of gas in the event of the pilot burner bec oming extinguished. This enables the supply of gas to the burner to be controlled independently as, for example, by a time switch which controls a solenoid in an electrically operated valve interposed between the block 22 and the valve assembly 28.

It will be appreciated that in orderto enable the pressure gauge 26 to give an accurate indication, as aforesaid, of the carbon dioxide output, the branch passage 25 is interposed between the filter 17a and the jet 17, close to the jet, the passage 21 being clear and unobstructed. This enables the gauge to give an accurate reading, unaffected by any progressive clogging of the filter or ducts leading thereto.

While what hereinbefore has been described as the preferred embodiment of this invention, it is readily apparent that alterations and modifications may be resorted to without departing from the scope of this invention and such alterations and modifications are intended to be included within the scopeof the appended claims.

4 What is claimed is: 1. Apparatus for increasing the carbon dioxide content of the atmosphere in spaces where plants are grown,

such as in glasshouses and other horticultural enclosuresv and the like, the apparatus comprising burner means for providing a substantially annular flame,

a skirt surrounding said burner means tecting the burner means from drafts,

a tray coupled to the lower end of said skirt, said tray being beneath and supporting said burner means and for catching burning foreign matter entering said apparatus, said tray having a large number of small perforations thereover to provide secondary aeration to said flame to cause said flame to curve upward and have a substantially saucer shape to permit substantially complete and controlled burning and to keep said flame fromimpinging upon said sldrt,

said burner means being supplied through a mixing tube extending centrally upwards through the tray and furnished with a jet for the admission of combustible gas and a hole for the admission of air, the jet being supplied through a substantially clear and unobstructed passage in a block having a filter at the inlet end of said block, and a branch passage in said block coupled with said unobstructed passage and close to said jet, said branch passage leading to a pressure gage responsive to the pressure in said block to provide an indication of the amount of carbon dioxide being generated, and

a canopy secured to said skirt to protect the burner from moisture or other matter that may fall on the apparatus, said canopy being substantially spaced above the upper end of said skirt for providing an unrestricted opening for allowing free flow of carbon dioxide from said flame outwards from said apparatus.

2. Apparatus for increasing the carbon dioxide content of the atmosphere in spaces where plant are grown, such as in glasshouses and other horticultural enclosures and the like, the apparatus comprising burner means for providing a substantially annular flame,

a skirt surrounding said burner means to assist in protecting the burner means from drafts,

a tray coupled to the lower end of said skirt, said tray being beneath and supporting said burner means and for catching burning foreign matter entering said apparatus, said tray having a large number of small perforations thereover to provide secondary'aeration to said flame to cause said flame to curve upward and have a substantially saucer shape to permit substantially complete and controlled burning and to keep said flame from impinging upon said skirt,

said burner means being supplied through a mixing tube extending centrally upwards through the tray and furnished with a jet for'the admission of combustible gas and a hole for the admission of air, the jet being supplied through a substantially clear and unobstructed passage in a block having a filter at the inlet end of said block, and a branch passage in said block coupled with said unobstructed passage and close to said jet, said branch passage leading to a pressure gage responsive to the pressure in said block to provide an indication of the amount of carbon dioxide being generated,

a thermostatic device for sensing the presence of a flame in the vicinity of the burner means and for cutting off the supply of fuel to the burner means if the flame is extinguished inadvertently, and

a canopy secured to said skirt to protect the burner to assist in profrom moisture or other matter that may fall on the apparatus, said canopy being substantially spaced above the upper end of said skirt for providing an unrestricted opening for allowing free flow of carbon 5 dioxide from said flame outwards from said apparatus.

References Cited UNITED STATES PATENTS 766,446 8/1904 Karle et a1. 126-85 837,471 12/1906 Humphrey 126-85 2,378,839 6/1945 Ensign et a1 158-118 X JAMES W. WESTHAVER, Primary Examiner. 

1. APPARATUS FOR INCREASING THE CARBON DIOXIDE CONTENT OF THE ATMOSPHERE IN SPACES WHERE PLANTS ARE GROWN, SUCH AS IN GLASSHOUSES AND OTHER HORTICULTURAL ENCLOSURES AND THE LIKE, THE APPARATUS COMPRISING BURNER MEANS FOR PROVIDING A SUBSTANTIALLY ANNULAR FLAME, A SKIRT SURROUNDING SAID BURNER MEANS TO ASSIST IN PROTECTING THE BURNER MEANS FROM DRAFTS, A TRAY COUPLED TO THE LOWER END OF SAID SKIRT, SAID TRAY BEING BENEATH AND SUPPORTING SAID BURNER MEANS AND FOR CATCHING BURNING FOREIGN MATTER ENTERING SAID APPARATUS, SAID TRAY HAVING A LARGE NUMBER OF SMALL PERFORATIONS THEREOVER TO PROVIDE SECONDARY AERATION TO SAID FLAME TO CAUSE SAID FLAME TO CURVE UPWARD AND HAVE A SUBSTANTIALLY SAUCER SHAPE TO PERMIT SUBSTANTIALLY COMPLETE AND CONTROLLED BURNING AND TO KEEP SAID FLAME FROM IMPINGING UPON SAID SKIRT, SAID BURNER MEANS BEING SUPPLIED THROUGH A MIXING TUBE EXTENDING CENTRALLY UPWARDS THROUGH THE TRAY AND FURNISHED WITH A JET FOR THE ADMISSION OF COMBUSTIBLE GAS AND A HOLE FOR THE ADMISSION OF AIR, THE JET BEING SUPPLED THROUGH A SUBSTANTIALLY CLEAR AND UNOBSTRUCTED PASSAGE IN A BLOCK HAVING A FILTER AT THE INLET END OF SAID BLOCK, AND A BRANCH PASSAGE IN SAID BLOCK COUPLED WITH SAID UNOBSTRUCTED PASSAGE AND CLOSE TO SAID JET, SAID BRANCH PASSAGE LEADING TO A PRESSURE GAGE RESPONSIVE TO THE PRESSURE IN SAID BLOCK TO PROVIDE AN INDICATION OF THE AMOUNT OF CARBON DIOXIDE BEING GENERATED, AND 